Process and apparatus for grouting porous formations



Feb. 26, 1957 s. WERTZ ETI'AL 2,782,505

- PROCESS AND APPARATUS FOR GROUTING POROUS FORMATIONS Filed Sept. 19, 1952 INVENTORS Louis S- W'ertz Lee TurziZLo PROCESS AND APPARATUS FUR GROUTING PGROUS FORMATIONS Louis S. Wertz, Shaker Heights, and Lee Turzillo, Bay

Village, Ohio, assignors, by direct and mesne assignments, to Intrusion-Prepakt, Incorporated, Cleveland, Ohio, a corporation of Delaware Application September 19, 1952, Serial No. 310,394 12 Claims. (Cl. 61-36) This invention relates to the solidification, densification, and strengthening of soft, porous, and loose earth and sand formations to enable them to resist heavier vertical and lateral pressures, to resist erosion by surface and underground water, to provide subsurface water barriers, etc.

Numerous methods and types of apparatus have been employed heretofore for stabilizing earth and sand formations in the respects mentioned to assist in the support of buildings, roadways, etc. above ground and to protect and/ or support subsurface operations or structures. The methods and apparatus employed for such purposes have varied greatly according to the particular conditions under which the work must be performed, the character of the earth formations to be worked upon, and the type and magnitude of the loads to be supported or forces to be resisted. All of such methods, however, have been subject in varying degrees to limitations restricting their use to certain types of working conditions, earth formations, and load resisting requirements.

Many of the methods heretofore employed have re quired the use of expensive and massive equipment. Most of them have required considerable headroom above the ground surface where the work is performed and have required, in many instances, the tedious sinking of some kind of permanent or temporary prefabricated casing or barrier, usually with the removal of more or less earth from the region to be worked upon. In general, the prior methods have been slow to perform, expensive to employ, and ineffective in one or more respects, depending upon the particular working conditions encountered.

The general object of the present invention is to provide improved and simplified methods and apparatus for solidifying, densifying, and strengthening soft, porous, and loose earth and sand formations to substantial depths.

A further object of the invention is to provide methods and apparatus for the purposes mentioned which are faster in operation and more easily adapted to meet the specified requirements of different jobs.

Still another object of the invention is to provide methods and apparatus for the purposes mentioned which do not require the removal of any earth or the leaving of expensive equipment in the formations on which the Work is performed.

A characteristic feature of the invention by which the foregoing objectives are accomplished involves the use of a rotatable drill that is adapted to be screwed into loose earth and sand with an action similar to that of an auger or propeller type cutter, the drill having a hollow shaft with openings adjacent its lower end through which water and grout may be pumped, and the drill shaft being built up of a plurality of short sections that may be coupled and uncoupled, one after another, as the drill is sunk and withdrawn. The lower end of the drill carries suitable cutting and/or mixing blades, and the openings adjacent the lower end of the shaft are located to discharge water or grout into the earth or sand closely adjacent these blades as they are rotating.

States Patent ()fiice 2,782,605 Patented Feb. 26, 1957 The drill is rotated to sink it into the earth or sand to the depth of the region to be worked upon, and, while continuing to rotate the drill, it is held there for a time and then withdrawn. A hydraulic cement grout for solidifying the earth is preferably pumped through the drill shaft as it is being sunk, and is ejected into the earth adjacent the lower end of the drill where it will be thoroughly stirred into soil as the drill blades descend therethrough. When the drill has been sunk to the required depth, the pumping of the grout may be discontinued or may be continued even during withdrawal of the drill, depending upon the character of the soil being Worked upon, the objective being to insure that the voids and interstices in the soil are filled as completely and uniformly as possible from the bottom of the region of the surface, or to any desired intermediate level, without removing any of the original soil.

This produces, when the grout has set, a generally cylindrical, solidified, densified, and strengthened, column like mass somewhat larger in diameter than the spread of the cutting and mixing blades on the drill. The region surrounding this column-like mass is also similarly affected to a degree that diminishes with the distance from the main body thereof and that varies with the porosity of the region and the grout pressure therein during the grouting operation. By repeating the foregoing procedure at suitable, horizontally spaced locations, a continuous, solidified region extending longitudinally as a wall, or laterally in all directions over any desired area, may be quickly and efliciently formed.

If the grout is not pumped through the drill shaft until the mixing blades on the lower end of the shaft have been sunk to a desired subsurface level, and the grout is then pumped during further downward travel of the mixing blades to a lower level, a subsurface pile will be formed that extends only between the two subsurface levels. By repeating this operation at points closely spaced horizontally over a selected area, a subsurface floor or blanket of concrete may be formed as a barrier to the upward flow of water, sand, silt, and the like during subsequent excavations of the soil above the floor or blanket. The invention may also be employed to form a continuous Wall surrounding such a subsurface floor and extending up to, or near, the surface, thereby forming the sides and bottom 'of a concrete shell, which may thereafter be emptiedof soil by excavation with complete safety.

The invention is also adapted for use in forming individual piles in situ in the earth at suitably spaced locations. In proper types of soil, such piles may be formed up to two or three feet, or more, in diameter by employing mixing heads of correspondingly large diameters.

The invention is further characterized by the use of a drill shaft made up of a number of relatively short lengths or sections and by the addition of section after section at the upper end thereof as the drill is worked downwardly, after which the uppermost sections are removed one after another as they emerge from the earth during withdrawal of the drill. This renders it possible to work under overhead structures or in similarly restricted places affording little head room and to perform and control the entire operation from a point substantially at the ground level, without constructing towers or elevated platforms, even though a shaft is being sunk to a great depth.

The invention is further characterized by novel apparatus adapted to be quickly attached to and detached from the upper end of each drill section in sequence for rotating the drill and simultaneously pumping a fluid therethrough, whereby the successive sections of the drill may be quickly added as it is being sunk and removed as it is being raised.

The foregoing and still further objects, features, and advantages of the invention will be better understood from the following detailed description of the methods and apparatus of the invention and from the accompanying drawing, in which:

Fig. 1 is a side elevation, partly in section, of a preferred form of apparatus employed for carrying out the present invention, the view showing the apparatus working in the earth;

Fig. 2 is a fragmentary elevation of the apparatus shown in Fig. 1, the view being taken as indicated by the line 2-2 in Fig. 1;

Fig. 3 is an elevation of the lowermost section or length of the drill string shown in Fig. 1;

Fig. 4 is a plan view of the apparatus shown in Fig. 3;

Fig. 5 is a fragmentary elevation of the device shown in Fig. 3; and

Fig. 6 is a horizontal section through the device shown in Fig. 3, the plane of the section being taken as indicated by the line6-6 in Fig. 3.

Referring to Figs. 1 and 2 of the drawing, there is shown a preferred type of apparatus, including a power mechanism 10 mounted on the rear end of a truck 11 or other suitable platform. The power mechanism 10 includes a suitable motor 12 and power transmitting mechanism 13 for supporting and rotating a vertically disposed shaft 14 in such a manner that the shaft may be moved axially as it is rotated. The lower end of the shaft is provided with any suitable form of chuck 16 for gripping a length of pipe extending through the hollow shaft 14 and causing it to rotate and move axially with the shaft 14.

The power mechanism 13 for driving the hollow shaft 14 may include any suitable gear train for rotating a driven gear mounted on the shaft 14 and connected thereto by means of a key or spline in the gear and a longitudinal slot in the shaft, whereby the shaft 14 may be rotated by the driven gear while remaining free to move in vertical directions with respect to the driven gear and the power mechanism. Since the details of this driving mechanism constitute no part of the invention and are found in commercially avialable equipment; such details have been omitted from the drawing and only briefly mentioned for the sake of simplicity.

Vertical movement of the hollow shaft 14 is preferably effected by means of a hydraulic ram or the like, which may include a pair of cylinders 18 mounted on opposite sides of the hollow shaft 14 and carried by the power mechanism. A pair of pistons (not shown) may be contained within the cylinders 18 and' connected by means of a pair of connecting rods 19 to a crosshead 21 secured to the hollow shaft 14 adjacent its upper end so as to permit the shaft to be rotated about its axis while constraining it to move along a vertical path with the crosshead 21. This connection may take any suitable form, such as an arrangement of collars 22 on the shaft 14 disposed on opposite sides of the crosshead 21.

As will be seen from the drawing and the foregoing description of this portion of the apparatus, the power mechanism is adapted to rotate the hollow shaft 14 about its axis, and the associated hydraulic mechanism is adapted to move the hollow shaft 14 upwardly and downwardly along a path determined by the permissible movement of the pistons in the cylinders18.

A drill string in the form of a plurality of separate lengths of hollow shaft, coupled together as a continuous conduit, is rotated and forced downwardly into the earth by the above described apparatus while pumping a fluid hydraulic cement grout downwardly through the hollow lengths of the drill string. A suitable drill string for such purpose may comprise a number of lengths 23 of conventional pipe, threaded at each end and connected together by a plurality of internally threaded sleeves 24, the successive lengths being added to the drill string in the manner hereinafter described as the drill string is forced downwardly into the earth.

The lower end of the drill string preferably comprises a similar, though somewhat shorter, length of pipe 26 that is externally threaded at its upper end and is closed at its lower end by a pointed plug 27 having a spiral groove or thread cut therein to enable it to serve as a lead screw and assist in penetrating the earth as the drill string is lowered. The plug may be rigidly secured to the lower end of the drill length 26 in any desired man ner, as by welding.

A plurality of pairs. of mixing and cutting blades are secured to the lower drill length 2.6- at spaced locations therealong, for assisting the penetration of the drill string into the earth and for mixing the earth as the lower end of the drill string moves therethrough. These blades are preferably arranged in pairs that project in opposite radial directions from the drill length 26, each successive pair of blades projecting at a different angle measured about the axis of the drill string, as best shown in Figs. 3 and 4. For clarity, the individual pairs of mixing blades are respectively designated by the reference characters 28a, 23b, 28c, 28d, 28e, 28f, and 28g.

Between the two pairs of blades 28a and 28b, a pair of elongated openings 29 are provided in opposite sides of the wall of the drill length 26, and a pair of conduits 31 are respectively secured to the drill length 26 in communication with the apertures 29 to receive grout ejected through these apertures from the hollow drill string. The conduits 31 extend downwardly and then outwardly along the sides of the lowermost blades 28a, respectively, and terminate in open ends 32 at about the longitudinal centers of these blades.

As shown in Fig. 3, each of the blades is a rigid bar of metal of substantially greater width than thickness and is inclined at such an angle that the lower edges of the blades will tend to cutinto the earth as the drill string is rotated in a clockwise direction, viewed from above. To increase the cutting action of the blades, their lower edges 33 may be sharpened, and the blades are preferably made of a hard, abrasion-resistant steel. By reason of the inclination of the blades 28ag, they perform an important mixing function as they are rotated in the earth as hereinafter described.

The lower open ends 32 of the conduits 31 are located substantially against the lower surfaces of the inclined blades 28a so that grout ejected from the conduits 31 as the drill string is rotated in a clockwise direction (viewed from above) will be deposited immediately behind the blades as they move through the earth. The movement of the blades through the earth tends to create voids behind the blades, and the grout ejected from the conduits 31, therefore, tends to fill these voids as they are created.

As shown in Figs. 1 and 2, the upper end of the drill string is held by the chuck 16 and passes upwardly above the chuck and through the hollow shaft 14 to a point above the shaft 14, where it is connected through a conventional swivel head 36 to a flexible grout conduit 37 fed with grout under pressure from any suitable supply. In this manner grout may be fed downwardly through the drill string from the conduit 37 while the drill string is being rotated and lowered into the earth by the driving mechanism described above.

When employing the foregoing apparatus for solidifying a subsurface mass of loose soil in accordance with the present invention, the lowermost drill length 26 carrying the cutting and mixing blades 28ag is first connected to the next higher drill length 23 while the latter is held in the chuck 16'and' extends upwardly through the hollow shaft 14 with the swivel head 36 and grout line 37 attached to its upper end. At the beginning of this operation the pistons are at the upper ends of their paths of travel in the cylinders 18, and the chuck is tightened about the drill length 23 passing therethrough. By rotating this portion of the drill string and simultaneously applying a downward force thereto, by means of the motor and hydraulic ram, the drill string is forced downwardly into the loose soil. At the same time, grout is pumped under a suitable pressure through the grout line 37 and through the drill string and is discharged into the soil through the open ends 32 of the conduits 31 immediately behind the lowermost blades 28a, as they are rotated. Each of the succeeding blades 28b-28g, as they follow the lowermost blades 28a downwardly through the soil, thoroughly mix the grout with the soil and produce a substantially homogeneous mixture of cement grout and soil particles.

When the drill string has been lowered as far as is permitted by the paths of travel of the pistons in the cylinders 18, the chuck 16 may be loosened, the ram may be raised, and the chuck retightened on the drill string for continuing its rotation and downward movement. When the upper end of the uppermost drill length 23 has been moved downwardly in this manner as far as is permitted by the swivel 36 on its upper end, the chuck 16 is loosened and the upper drill length is unscrewed from the sleeve 24 that connects it to the lowermost drill length 26. The ram is then raised and an additional drill length 23 and sleeve 24 are inserted between and secured to the lowermost drill length 26 and the uppermost drill length 23, respectively. The chuck is then again tightened on the uppermost drill length 23 and the process of rotating and driving the drill string through the earth is continued. Additional drill lengths 23 and sleeves 24 are inserted from time to time in the same manner as the drill progresses downwardly, and grout is preferably pumped through the drill shaft and into the soil continuously during the actual downward movement of the drill string.

When grout has been discharged into and mixed with the soil in the manner described above to the desired depth, the flow of grout may be terminated, and the drill string may be raised by the hydraulic ram, preferably while continuing to rotate it in the same direction, whereby the mixing blades perform a second mixing operation as they ascend. in this manner maximum homogeneity of the mixture of grout and soil is obtained, and a column 38 of soil mixed with grout is produced which solidifies into a hardened concrete column as the grout sets.

When the drill string has been completely withdrawn, the same process may be repeated as close to the preceding location of the drill string as desired. Any desired number of such columns may be formed at intervals over any given area or along a desired line to solidify an entire region or to form asolidified subsurface wall. The diameter of each column solidified in this manner Will normally be slightly greater than the combined length of each pair of blades 28ag, depending upon the per meability of the soil to the grout and upon other obvious factors. In most instances it will be found desirable to locate the successive solidified ,columns sufliciently close together so that they are either tangent to each other or actually overlap, particularly if the solidified mass is intended to act as a water barrier. However, the spacing of the solidified columns may be varied according to the needs of the particular project.

In some instances, depending upon the character of the soil being worked upon, it may be desirable to pump grout through the drill string both while it is being driven into the earth and while it is being withdrawn to insure complete filling of all voids in the soil. This is seldom necessary, however, since substantially complete filling of the voids is generally accomplished while driving the drill string into the earth.

From the foregoing description of the invention and preferred apparatus and procedural steps for carrying it out in practice, it will be apparent that we have provided a novel and simple method and apparatus for solidifying, densifying, and strengthening soft, porous, and loose earth and sand formations to substantial depths, and that the method may be carried out rapidly and efficiently without the employment of expensive or massive equipment and without the necessity for leaving any of the equipment in the earth after the work has been performed. It will also be apparent that the various ways in which the invention may be employed adapt it for the solidification of.

prising the steps of rotating a shaft having an elongated sidewardly extending blade about an axis while simultaneously advancing it axially into the earth so that said blade progressively moves and loosens the soil in advance of its rotational movement, and forcing a liquid solidifying agent into the earth adjacent the blade, the rotation of the blade mixing the soil with the solidifying agent.

2. The combination of claim 1 wherein said shaft and blade are withdrawn axially while continuing to rotate same to efiect a further mixing.

3. The process of claim 2 wherein said agent is also forced into the earth as said blade is withdrawn.

4. A method for solidifying columns in the earth by mixing the soil in situ with a liquid solidifying agent comprising the steps of rotating a shaft having an elongated sidewardly extending blade about an axis while simultaneously advancing it axially into the earth to continuously create a cavity behind said blade, simultaneously forcing a liquid solidifying agent into the earth adjacent the blade and thus into the cavity so that said blade progressively moves the soil from its path of its rotational movement and mixes it with the previously deposited solidifying agent.

5. The method of claim 4 wherein said method is repeated at suitable horizontally spaced locations to provide a continuous solidified region extending longitudinally as a wall or laterally in all directions over any desired area.

6. The method of claim 4 wherein said method is repeated at points closely spaced horizontally over a selected area to provide continuous adjacent columns of solidified soil.

7. A method for solidifying columns in the earth by mixing the soil in situ with a liquid solidifying agent, comprising the steps of rotating a member having an elongated sidewardly extending blade in the earth to create a cavity behind the blade by moving the earth from its path simultaneously flowing a liquid solidifying agent into said cavity as it is formed and simultaneously advancing said member through the earth so that the path of movement if succeeding revolutions is axially displaced from the pervious paths of movement whereby soil in advance of such subsequent movements is displaced and mixed with agent flowed into the cavity formed by previous paths of movement.

8. A tool for solidifying columns in the earth by mixing the soil in situ with a liquid solidifying agent, com prising in combination an elongated rotatable shaft, an elongated sidewardly projecting blade on the lower end of said shaft adapted to create a cavity in the earth as the shaft is rotated and advanced into the earth, and a closed passage extending the length of the shaft having an opening adjacent the blade end thereof and adapted to have a liquid solidifying agent pumped therethrough under pressure and into the cavity created by movement of the blade.

9. The combination of claim 8 wherein said arm is pitched to draw said shaft into the earth as the shaft is rotated.

10. The combination of claim 8 wherein a plurality of axially spaced blades on said shaft are provided.

11. Apparatus for solidifying columns in the earth by mixing the soil in situ with. a liquid solidifying agent, comprising in combination an elongated rotatable shaft, an elongated sidewardly projecting; blade on the lower end of said shaft, means for rotating said shaft and blade in,

the earth whereby to create. cavities in the earth, behind the blade, a passageextending the. length of said shaft having an opening adjacent the lower end thereof through which a solidifying agent under pressure may be discharged into the earth and flow into the cavity created by the rotation of the blade, means for pumping a solidifying agent through said passage and means for simultaneously advancing. said shaft into the earth at a rate. such that subsequent sweeps ofthe rotating blade mix the soil with they solidifying agent previously injected,

12. The combination of claim 11 wherein said blade is pitched to draw the shaft into the earth as it is rotated.

I References Cited in the, file of this patent UNITED STATES PATENTS 710,619 Sharpless Oct. 7, 1902 874,292 Clackford Dec. 17, 1907 935,081 Wolfsholz Sept. 28, 1909 1,919,844 Kinnear July 25, 1933 2,203,881 Schwab et a1 June 11, 1940 FOREIGN PATENTS 405,767 Great Britain Feb. 16, 1934 

